Field
Embodiments according to the present disclosure relate to flow control devices for use in oil and gas wells, and particularly to flow control devices used for isolating the portion of the well above the device from portions below the device. Such flow control devices may be used to isolate one region of the wellbore, and/or tubing installed in the wellbore, from other portions thereof and are commonly used in the completion of multiple formations accessed by a single well, multiple stage completions of a single formation, or other activities in which it is desirable to prevent fluid communication across a desired location within the well.
Description of Related Art
Current devices, such as frac plugs and bridge plugs, for preventing fluid communication across a location in a well are not totally satisfactory. Such devices may be limited to fluid isolation with relatively low pressure differentials, have an unsatisfactorily small (or non-existent) flow path therethrough when the device is an “open” state, require active intervention—such as mill-out or release—for their removal, utilize materials that take longer than is acceptable to mill out (e.g. have unacceptable machinability), have an excessive volume of material to be milled because of cross-sectional thickness and/or length, or combinations of these and other limitations.
Some such fluid barriers, such as bridge plugs, must be removed from the well, such as by drilling or milling out, before fluids can flow back from the formation to the wellhead. The bridge plugs function as fluid barriers in both directions, preventing fluid flow not only from the wellhead to the previously treated portion(s) of the well, but also from such treated portions to the wellhead. Drilling out bridge plugs can be a time consuming and expensive process involving workover rigs or coil tubing.
One alternative to bridge plugs and frac plugs is the baffle. These devices have an open throughbore that can be sealed with an appropriately sized ball, dart or other plug to prevent fluid flow from the wellhead to the formation. Higher pressure on the wellhead side of the baffle forces the plug into the baffle and the plug releases when pressure equalizes across the baffle or when pressure on the downwell side is greater than the upwell side. In this way, baffles may permit reservoir fluids to flow to the wellhead without the drilling out operation required for bridge plugs and frac plugs. Present baffle designs have a throughbore that is unsatisfactorily narrow, which may lead to clogging—such as “sanding up” or other blockage—following completion of fracture treatments, such as during flowback. Further, the narrow throughbore limits the thru tubing tools that may pass through such baffles so that, even if such baffles may remain during initial production, they are likely to require drilling out when workover operations become necessary.